Year	gross (GPI)
1973	0.596660017967224
1974	0.90149998664856
1975	0.919489979743958
1976	0.826910018920898
1977	0.931299984455109
1978	1.04135000705719
1979	0.990790009498596
1980	0.959959983825684
1981	0.902239978313446
1982	0.961510002613068
1983	0.946110010147095
1984	0.924440026283264
1985	0.934249997138977
1986	0.953849971294403
1987	1.08069002628326
1988	1.153480052948
1989	1.18863999843597
1990	1.19290995597839
1991	1.16970002651215
1992	1.15743005275726
1993	1.12715995311737
1994	1.08768999576569
1995	1.05437004566193
1997	1.10571002960205
1998	1.12578999996185
2016	0.958840012550354
2017	0.918699979782104
2019	0.986909985542297
2020	1.01218998432159